Stacked PRs are an indicator of an incompletely thought out approach to the implementation. Prefer sequential PRs that layer in the implementation: test code, interfaces/API stubs, and then concrete implementations of the stubs (for example). This tends to make PRs less complex and more inviting for colleagues to review, which in my experience tends to make them go much faster. It also leads to generally better code quality.
But how can you write the concrete implementation without stacking?
The only thing stacked PRs indicate, IMO, is that your coworkers are slow to review your code.
And in my experience, when folks send out stacked PRs, it’s because they put much _more_ thought and effort into identifying the right boundaries, not less.
